FIG. 6 is a diagram showing the configuration of a dynamometer system 100. The dynamometer system 100 includes: an engine E which serves as a test piece; a dynamometer D which serves as a power absorbing member; a coupling shaft S which couples the engine E and the dynamometer D together; an engine control device 120 which controls the engine E through a throttle actuator 110; a dynamo control device 140 which controls the dynamometer D through an inverter 130; an encoder 150 which detects the rotation speed of the output shaft of the dynamometer D; and a shaft torque meter 160 which detects shaft torque (torsion torque) in a coupling portion of the coupling shaft S and the output shaft of the dynamometer D.
The engine control device 120 controls the output of the engine E in a form which is previously determined for each test item, and the dynamo control device 140 controls the rotation speed of the dynamometer D and torque based on the outputs of the encoder 150 and the shaft torque meter 160 and the like (see, for example, Patent Document 1).
Incidentally, in the dynamometer system 100 as described above, when the engine speed at the time of start of the engine is controlled to correspond to the engine speed at the time of start of the engine alone, it is necessary to perform the control so as to achieve a no-load state where the coupling shaft S and the dynamometer D are not connected when seen from the engine E. Patent Document 2 discloses a dynamo control device which performs control such that torsion torque in a coupling shaft S between an engine E and a dynamometer D is 0 [Nm] and which thereby realizes such a no-load state.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2003-149085
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2015-075361